[clang-c] Don't deprecate CXRemapping as well as its users (llvm#149975)

llvm#149079 deprecated CXRemapping and all its methods, however MSVC warns
when a deprecated method is using a deprecated variable (and breaks our
Werror builds) - best way to avoid this is to only deprecate the methods
directly.

Author: RKSimon

clang/include/clang-c/Index.h

@@ -6953,7 +6953,7 @@ clang_getCursorUnaryOperatorKind(CXCursor cursor);
  * @}
  */
 
-CINDEX_DEPRECATED
+/* CINDEX_DEPRECATED - disabled to silence MSVC deprecation warnings */
 typedef void *CXRemapping;
 
 CINDEX_DEPRECATED CINDEX_LINKAGE CXRemapping clang_getRemappings(const char *);